1. Technical Field
The present invention relates in general to the field of computers, and, in particular, to the connection of an external data storage device to a computer. Still more particularly, the present invention relates to an improved system for allowing a computer to share common interface pins to connect the computer to either a serial data interfacing external data storage device or a parallel data interfacing external data storage device.
2. Description of the Related Art
Historically, computers have typically connected to an external data storage device, such as a magnetic storage hard disk or an optical drive such as a Compact Disc-Read Only Memory (CD-ROM), via a parallel interface bus. The most popular bus for this parallel interface is the Advanced Technology (AT) Attachment/Integrated Drive Electronics (ATA/IDE) parallel bus, which is used to connect external data storage devices that have an integrated controller to control the transfer of data from the computer to the external data storage device.
More recent computers may have both parallel and serial data interfaces to external data storage devices, and in the future are expected to have only serial data interfaces. To provide appropriate electrical and mechanical interfacing, separate pin connectors are required for parallel and serial connections. These additional pins for accommodating different interfaces are expensive, especially when competing for space in smaller laptop and palmtop computers, as well as in a docking station for such computers. Further, additional pins may be required to signal from the external data storage device to the computer whether the external data storage device can receive data in the form of parallel, serial or both.
It should therefore be apparent that there exists a need for a method and apparatus that provides an electrical interface between the computer and the external data storage device that allows the use of common interface pins in the interface between the computer and the external data storage device whether the external data storage device communicates via serial or parallel data lines. Such shared usage of computer/device interface pins would allow not only conservation of pins, but would also allow computers that use external data storage devices in parallel only, parallel or serial, or serial only form to use the same docking station and/or storage device interface.